In systems known on the market, the size of the treatment booth, often a painting booth, in which the object is painted is adapted to the length and shape of the objects to be treated. This means that the object is put entirely inside the treatment booth and undergoes surface treatment there. Rather than being painted, this treatment may also mean, for example, drying of a coating which has already been applied to the object, cleaning of the surface thereof or similar.
When objects are painted, not all the paint applied reaches the object. Some of the paint is deposited in the interior of the booth, as so-called paint overspray. To remove this from the booth, air is fed through the painting booth and carries the paint overspray along with it. The air absorbing the paint overspray is then supplied to a processing step. In the case of a painting booth as the treatment booth, means of controlling the air management are therefore necessary.
If very large objects, which may have a length of 50 m or more, are to be painted, such as rotor blades for wind turbines, correspondingly large painting booths have to be built so that these objects can be entirely contained. Painting is carried out by means of application robots, which are known per se. The latter have to be able to move along the stationary object to be painted at a constant speed so that all the regions of the object can be coated in a reliably even manner. Usually, seven-axis robots are used, the seventh axis being the axis of movement.
A large-scale booth of this kind requires large quantities of air, which can only be handled using correspondingly complex and large and hence high-cost ventilation systems. Moreover, the system as a whole is very long if operation is by passage through it, which is desirable from the point of view of a high throughput through the system. Typically, a length at least three times that of the object to be coated is required. As well as the painting booth, on the one hand a region upstream thereof and on the other a region downstream thereof is required, each one having to be as long as the object to be painted. Only in this way can the object be moved upstream of the entry to the treatment booth and, after treatment, be taken away from the system downstream of the exit from the treatment booth without difficulty.
To save space in the case of a system operated by passage through it, however, it is only possible to construct the treatment booth to be shorter. There is no room for adjustment upstream and downstream of the treatment booth.
Although it is possible in the case of a treatment booth, in particular a painting booth, which is shorter than the object to be treated to use fixed application robots, which makes it easier to control the painting procedure, the disadvantage in this case is that the object must be conveyed through the painting booth and past the application robots evenly and as far as possible without jolting, in order to ensure that the object is coated evenly.
If a pulling or pushing means such as a chain provides the drive for a long object over the entire transport path thereof—in other words, if the drive distance is the same as the transport distance—then typically jolting while the object is being moved is unavoidable, however, in particular at low speeds. This is not acceptable in the case of a painting booth that is shorter than the object to be painted, however, since the result would be a relatively poor painting outcome.
The present invention is directed to resolving these and other matters.